Military Time Converter with a Full Day Chart
Military Time Converter
Type into either box and the other follows. Handles 1430, 14:30, 2:30 PM and bare hours, tells you when an entry is impossible, and converts a whole pasted list in one go.
| 24 hour | 12 hour | Spoken | 24 hour | 12 hour | Spoken |
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How to use this tool
Type in either box. The other one keeps up as you go, so you can work in whichever direction you are thinking. The 24 hour box takes 1430, 14:30, or just 14 for the hour on the hour. The 12 hour box takes 2:30 PM, 230 pm, or 2 pm. Case and spacing do not matter and a trailing full stop in “p.m.” is ignored.
If you have a roster, a flight list or a set of log entries, paste the lot into the bulk box. Each line is converted on its own and anything unreadable is called out in red rather than quietly skipped, which matters when you are checking a shift pattern and one row is a typo. The table at the bottom is the whole day in one screen, and it is the thing to print and stick on a wall if you are learning this.
What the conversion is actually doing
Going from 12 hour to 24 hour is two rules and one exception each way. For AM times, the hour stays as it is, except 12 AM which becomes 00. For PM times, add 12 to the hour, except 12 PM which stays 12. Coming back the other way: hours 13 to 23 lose 12 and take PM, hours 01 to 11 keep their number and take AM, 00 becomes 12 AM and 12 becomes 12 PM.
Minutes never change. That is worth saying because it is the part people trust least when they are new to it. Half past four in the afternoon is 1630 and the 30 is the same 30 it always was.
Why 12 is the number that causes all the trouble
AM and PM are short for ante meridiem and post meridiem, before midday and after midday. Meridiem is the moment itself, noon. So the 12 hour clock is really counting hours away from noon and midnight, and the labels tell you which side of noon you are on.
The problem is that noon and midnight are neither before nor after themselves. They are the boundaries. A strictly logical system would call noon neither AM nor PM, and some style guides do exactly that by insisting on the words noon and midnight instead. What we actually do is a convention that has to be memorised: the hour that starts at midnight is called 12 AM, and the hour that starts at noon is called 12 PM. There is no derivation. It is just what everyone agreed.
The 24 hour clock removes the argument by never using 12 as a marker. It counts hours elapsed since midnight, from 00 to 23, and there is exactly one name for every minute of the day. That is why hospitals, airlines, the military and most of the world outside North America use it. The cost of that clarity is a system where 1900 hours takes a moment of thought, and the benefit is that nobody has to ask whether a 12:00 deadline is lunchtime or the small hours.
The last wrinkle is 2400. Both 0000 and 2400 name the same instant. The convention is that 0000 opens a day and 2400 closes the previous one, so a shift running 1600 to 2400 ends at the same moment a shift starting 0000 begins. Contracts and timesheets use 2400 for exactly this reason, because “ends at 0000 on the 5th” is ambiguous about which night is meant. This tool accepts 2400, tells you it has read it as an end of day, and normalises it to 0000 for the arithmetic.
A worked check you can repeat on paper
The tool loads with 1430. Because 14 is greater than 12, take 12 off it: 14 minus 12 is 2, and being past noon it is PM. The minutes are untouched. So 1430 is 2:30 PM. Read it out as fourteen thirty hours.
Now try the two hard ones. For 12:05 AM, the AM rule says the hour stays put except 12 becomes 00, so it is 0005. Five minutes past midnight, right at the start of the day. For 12:05 PM, the PM rule says add 12 except 12 stays 12, so it is 1205. Five minutes past noon. Those two entries look almost identical on a form and are twelve hours apart, which is how a meeting gets missed.
One more as a check on the minutes past midnight figure. For 1815, that is 18 hours and 15 minutes since midnight, so 18 times 60 is 1080, plus 15 is 1095. The tool shows 1095, and that number is the one to use if you are subtracting one time from another, because minute counts subtract cleanly and clock faces do not.
Mistakes that catch people out
- Writing midnight as 1200. The single most common error, and it puts an event twelve hours out. Midnight is 0000. If you find yourself writing 12 in the 24 hour form for anything other than noon, stop.
- Assuming PM starts at 1 PM. It starts at 12 PM, the noon hour. So 12:30 PM is 1230, not 0030.
- Typing 2530 for half past one in the morning. Hours stop at 23. Times after midnight belong to the next day and start again at 0000, so it is 0130.
- Dropping the leading zero. 730 and 0730 both read fine here, but on a form or in a filename 730 sorts after 1200 and before 800, which quietly scrambles a chronological list. Always pad to four digits.
- Adding a colon and calling it military time. 14:30 is perfectly clear and this tool accepts it, but strict military usage writes 1430 with no separator, and says the word hours after it.
- Subtracting times as if they were numbers. 1300 minus 1145 is not 155. Convert both to minutes past midnight, 780 and 705, subtract to get 75 minutes, then turn that back into 1 hour 15.
How this was checked
The parser was written twice and the two versions compared. Beyond the obvious cases, every one of the 1440 minutes in a day was converted to the 12 hour form and parsed back again, and all 1440 returned the exact hour and minute they started with. That sweep is the only way to be sure the noon and midnight rules are right in both directions rather than just in the direction you happened to test. The rejections were checked too: 2500, 1265, 13:00 PM and 0:00 PM all come back as invalid rather than being silently coerced into something plausible, which is the failure mode that does real damage on a roster.
Related Calculators and Reference
- Timesheet duration calculator once the times are in one format, this works out hours worked and splits the overtime.
- Date difference calculator for spans measured in days rather than minutes, including the awkward month ends.
- Working days calculator for rosters that need to skip weekends and public holidays.
- Add or subtract days calculator for shifts that run past midnight into the following date.
- Age calculator the same calendar arithmetic applied to a birth date.
- Time Calculator: add hours to a clock time or find the time between two times.
- Time Zone Converter: convert times between cities and time zones.
- NIST time and frequency FAQ the national metrology institute on why noon and midnight are ambiguous in the 12 hour system and what to write instead.